Nitrogen-Fixing Nodules Are an Important Source of Reduced Sulfur, Which Triggers Global Changes in Sulfur Metabolism in Lotus japonicus

作者：Kalloniati Chrysanthi; Krompas Panagiotis; Karalias Georgios; Udvardi Michael K; Rennenberg Heinz; Herschbach Cornelia; Flemetakis Emmanouil^*

来源：Plant Cell, 2015, 27(9): 2384-2400.

DOI：10.1105/tpc.15.00108

We combined transcriptomic and biochemical approaches to study rhizobial and plant sulfur (S) metabolismin nitrogen (N) fixing nodules (Fix(+)) of Lotus japonicus, as well as the link of S-metabolism to symbiotic nitrogen fixation and the effect of nodules on whole-plant S-partitioning and metabolism. Our data reveal that N-fixing nodules are thiol-rich organs. Their high adenosine 5'-phosphosulfate reductase activity and strong S-35-flux into cysteine and its metabolites, in combination with the transcriptional upregulation of several rhizobial and plant genes involved in S-assimilation, highlight the function of nodules as an important site of S-assimilation. The higher thiol content observed in nonsymbiotic organs of N-fixing plants in comparison to uninoculated plants could not be attributed to local biosynthesis, indicating that nodules are an important source of reduced S for the plant, which triggers whole-plant reprogramming of S-metabolism. Enhanced thiol biosynthesis in nodules and their impact on the whole-plant S-economy are dampened in plants nodulated by Fix(-) mutant rhizobia, which in most respects metabolically resemble uninoculated plants, indicating a strong interdependency between N-fixation and S-assimilation.

• 出版日期2015-9